Show Selection: |
#110349 (Received by flhurricane at: 4:49 AM 12.Sep.2006) TCDAT2 TROPICAL STORM GORDON DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072006 500 AM EDT TUE SEP 12 2006 THE CENTER IS DIFFICULT TO LOCATE IN INFRARED IMAGERY...AND THERE HAVEN'T BEEN ANY GOOD MICROWAVE PASSES RECENTLY. CONTINUITY FROM THE PREVIOUS MOTION WOULD PLACE THE CENTER NEAR THE SOUTHERN EDGE OF A SMALL BALL OF DEEP CONVECTION. THE ASSUMED INITIAL MOTION IS 320/7...ALTHOUGH IS POSSIBLE THE CENTER IS A LITTLE TO THE NORTHEAST OF THE ADVISORY POSITION. GORDON IS LOCATED ON THE SOUTHWESTERN PERIPHERY OF MID- LEVEL HIGH PRESSURE...WITH A PRONOUNCED BREAK IN THE SUBTROPICAL RIDGE ASSOCIATED WITH FLORENCE TO ITS NORTHWEST. ANOTHER IMPORTANT FEATURE IS A LARGE UPPER-LEVEL LOW...LOCATED ABOUT 1000 NMI TO THE EAST-NORTHEAST OF GORDON...THAT IS MOVING WESTWARD. GLOBAL MODELS INDICATE THAT EVEN THOUGH FLORENCE WILL BE MOVING OUT...THE WESTWARD-MOVING UPPER LOW WILL BREAK DOWN THE REMAINING SUBTROPICAL RIDGE TO THE NORTH OF GORDON AND ALLOW THE CYCLONE TO SLOWLY RECURVE. MOST OF THE DYNAMICAL MODELS SUPPORT THIS SCENARIO... ALTHOUGH THE GFS IS THE RIGHT OUTLIER INITIALLY AND CONSEQUENTLY HAS A MUCH SLOWER INTERACTION WITH THE WESTERLIES. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY TRACK EXCEPT A LITTLE SLOWER TO THE NORTHEAST ON DAYS 4 AND 5 OUT OF RESPECT FOR THE GFS. OVERALL THE TRACK IS IN BEST AGREEMENT WITH THE UKMET AND NOGAPS MODELS. DVORAK INTENSITY ESTIMATES ARE 45...55...AND 55 KT FROM TAFB... SAB...AND AFWA...RESPECTIVELY...AND THE ADVISORY INTENSITY WILL REMAIN AT 50 KT. THE UPPER-LEVEL FLOW OVER GORDON IS DIVERGENT... AND THIS FAVORABLE PATTERN IS FORECAST BY THE GLOBAL MODELS TO PERSIST FOR THE NEXT COUPLE OF DAYS. THE SHIPS AND GFDL INTENSITY MODELS BOTH BRING GORDON UP TO ABOUT 80 KT IN 48 HOURS...AND THE OFFICIAL FORECAST DOES AS WELL. ONE POSSIBLE INHIBITING FACTOR WOULD BE SOME DRY MID-LEVEL AIR THAT COULD BE DRIVEN INTO THE CYCLONE FROM THE NORTHEAST BY THE UPPER-LEVEL LOW. TOWARD THE END OF THE FORECAST PERIOD...AS THE CYCLONE BEGINS TO RECURVE OVER COOLER WATERS AND ENCOUNTERS WESTERLY SHEAR...THE INTENSIFICATION OF GORDON SHOULD BE DONE. FORECAST POSITIONS AND MAX WINDS INITIAL 12/0900Z 22.6N 58.3W 50 KT 12HR VT 12/1800Z 23.6N 59.0W 55 KT 24HR VT 13/0600Z 25.1N 59.5W 65 KT 36HR VT 13/1800Z 26.7N 59.6W 75 KT 48HR VT 14/0600Z 28.1N 59.5W 80 KT 72HR VT 15/0600Z 30.5N 58.5W 80 KT 96HR VT 16/0600Z 33.0N 57.0W 75 KT 120HR VT 17/0600Z 37.0N 52.0W 65 KT $$ FORECASTER FRANKLIN |